Flying to the UK could be hazardous to your health! I know, there are lots of statistics suggesting that flying is safer than crossing the road. Strangely, flying to the UK from Europe is perfectly safe, but flying to the UK from North America poses a very real threat to your long term health.
The reason for this strange phenomenon is to be found in the science of astrophysics. I won't bore you with the science in this post; I'll just keep it simple. The galaxy in which our Sun and the Earth are located is a dangerous source of cosmic rays. These are the highly dangerous form of radiation that would quickly kill astronauts if they were not adequately protected. The Earth's magnetic field shields us from cosmic rays to some extent, but it doesn't do so evenly all over the planet.
The safest place on Earth is at the equator where the Earth's magnetic field lies parallel to the Earth's surface repelling the rays quite effectively. But, at the north and south magnetic poles the Earth's magnetic field runs perpendicular to the surface, drawing the cosmic rays down towards the ground.
Planes flying between Canada and the UK take a polar route flying very close to the region where cosmic rays are concentrated down towards the Earth's surface. Cosmic radiation is naturally higher at greater altitudes so flyers incur the double jeopardy of altitude and latitude leading to increased radiation exposure.
But don't worry; you will only spend a couple of hours in the high cosmic radiation zone - unless you are a member of a flight crew and work the transatlantic route regularly.
Footnote: Regular readers know that not everything they read on this blog is to be taken literally; I do like to have a little mischievous fun from time to time. However, today's science bulletin is not one of those occasions. It is taken from a very serious scientific book that I have read recently. Send me a comment (using the link at the bottom of the post) if you would like to be sent the reference details.